The seasonal size structure and spatial abundance distributions of Euphausia pacifica populations were investigated in the central part of southern Yellow Sea from August 2009 to May 2010.The abundance and biomass of ...The seasonal size structure and spatial abundance distributions of Euphausia pacifica populations were investigated in the central part of southern Yellow Sea from August 2009 to May 2010.The abundance and biomass of E.pacifica were higher in spring and summer,and lower in autumn and winter.The mean abundance and biomass(calculated by carbon)were 74.94 ind./m^3 and 8.23 mg/m^3,respectively.Females with total length(TL)ranging between 10 and 19 mm in summer had a substantial contribution to the population biomass,whereas larvae of TL of 3–7 mm in spring were the main contributor to the population abundance.The sex ratio(female:male)showed a female bias in four seasons.Its value peaked in summer,and then decreased in autumn,spring,and winter successively.Cohort analysis revealed that the length-frequency distribution of E.pacifica could be characterized as one group with large animals(mean TL>12 mm)accompanied by one or two subgroups of small individuals(mean TL<7 mm).Regarding the spatial distribution,juveniles and adults of E.pacifica tend to concentrate in relatively deep water with low temperature(～11℃)and high salinity(>32),whereas its larvae showed more abundance in inshore water with rich chlorophyll a,low salinity(<32),and warm temperature(>11℃),especially in summer and autumn.Associations changed seasonally between stage-specific abundance and environmental factors.展开更多
太平洋磷虾是黄海生态系统中浮游动物的关键种。为准确评估太平洋磷虾的资源密度,基于2010年1月黄海渔业资源调查过程中采集的声学和生物学数据,利用SDWBA目标强度理论模型,研究了太平洋磷虾38和120 k Hz目标的回声散射特性,并根据2个...太平洋磷虾是黄海生态系统中浮游动物的关键种。为准确评估太平洋磷虾的资源密度,基于2010年1月黄海渔业资源调查过程中采集的声学和生物学数据,利用SDWBA目标强度理论模型,研究了太平洋磷虾38和120 k Hz目标的回声散射特性,并根据2个频率平均体积散射强度的差值(简称频差技术),开展了太平洋磷虾回波映像识别及资源密度评估研究。结果显示,太平洋磷虾的目标强度与其倾角和体长密切相关;120k Hz的目标强度明显高于38 k Hz,且两个频率的有效平均目标强度之差随着磷虾体长的增加而减小。数据处理结果显示,两个频率回声数据的平均体积散射强度(MVBS)呈线性关系,120 k Hz的MVBS比38 k Hz高约14.1 d B,与理论仿真结果一致;回声散射层内太平洋磷虾的资源密度为1.8~2531.8尾/m3,均值为255.1尾/m3。本研究对利用渔业声学技术开展浮游动物资源评估具有借鉴意义,未来还需要进一步对太平洋磷虾目标强度模型参数及目标识别方法进行完善,以提高其资源密度声学评估的准确度。展开更多
基金The NSFC-Shandong Joint Fund for Marine Science Research Centers under contract No.U1606404the National Natural Science Foundation of China under contract No.40976103the Ministry of Science and Technology of China under contract No.2011CB403604
文摘The seasonal size structure and spatial abundance distributions of Euphausia pacifica populations were investigated in the central part of southern Yellow Sea from August 2009 to May 2010.The abundance and biomass of E.pacifica were higher in spring and summer,and lower in autumn and winter.The mean abundance and biomass(calculated by carbon)were 74.94 ind./m^3 and 8.23 mg/m^3,respectively.Females with total length(TL)ranging between 10 and 19 mm in summer had a substantial contribution to the population biomass,whereas larvae of TL of 3–7 mm in spring were the main contributor to the population abundance.The sex ratio(female:male)showed a female bias in four seasons.Its value peaked in summer,and then decreased in autumn,spring,and winter successively.Cohort analysis revealed that the length-frequency distribution of E.pacifica could be characterized as one group with large animals(mean TL>12 mm)accompanied by one or two subgroups of small individuals(mean TL<7 mm).Regarding the spatial distribution,juveniles and adults of E.pacifica tend to concentrate in relatively deep water with low temperature(～11℃)and high salinity(>32),whereas its larvae showed more abundance in inshore water with rich chlorophyll a,low salinity(<32),and warm temperature(>11℃),especially in summer and autumn.Associations changed seasonally between stage-specific abundance and environmental factors.
文摘太平洋磷虾是黄海生态系统中浮游动物的关键种。为准确评估太平洋磷虾的资源密度,基于2010年1月黄海渔业资源调查过程中采集的声学和生物学数据,利用SDWBA目标强度理论模型,研究了太平洋磷虾38和120 k Hz目标的回声散射特性,并根据2个频率平均体积散射强度的差值(简称频差技术),开展了太平洋磷虾回波映像识别及资源密度评估研究。结果显示,太平洋磷虾的目标强度与其倾角和体长密切相关;120k Hz的目标强度明显高于38 k Hz,且两个频率的有效平均目标强度之差随着磷虾体长的增加而减小。数据处理结果显示,两个频率回声数据的平均体积散射强度(MVBS)呈线性关系,120 k Hz的MVBS比38 k Hz高约14.1 d B,与理论仿真结果一致;回声散射层内太平洋磷虾的资源密度为1.8~2531.8尾/m3,均值为255.1尾/m3。本研究对利用渔业声学技术开展浮游动物资源评估具有借鉴意义,未来还需要进一步对太平洋磷虾目标强度模型参数及目标识别方法进行完善,以提高其资源密度声学评估的准确度。
